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You and me, baby, ain't nothing but mammals

The song of the title of this post is a catchy and highly amusing piece that suggests that if we’re just mammals we should have sex. It’s sort of a low brow version of Andrew Marvell’s To his coy mistress. Instead of Time’s wingéd chariot, we should do what mammals do on the Discovery Channel. Except, humans don’t. They do something special. Think about it. We aren’t dogs, monkeys, dolphins or bowerbirds, we’re humans. We are a species (which, as I keep reminding folk, is the noun of “special”).

So when Phillip Johnson, the father of the modern intelligent design movement, attacks Christopher Hitchens for calling “great men” “mammals”, and points out:

While Hitchens never refers to the authorities on his side as “mammals,” reserving that category for those whom he wishes to belittle, it will not escape the reader that if “great men” are only mammals, then so are scientists, including the esteemed Charles Darwin and the not-quite-so-esteemed Richard Dawkins, and so, of course, is Hitchens himself. Which raises the question: Why should we take seriously any speculation by a mere mammal, or even the consensus of mammal opinion, about the origin of its species, no matter how much evidence the mammals imagine themselves to have gathered?

… we might be inclined to agree. If we’re just mammals, then we shouldn’t pay attention to Hitchens or Dawkins or Darwin, right?

I call this Darwin’s Monkey Mind Puzzle. Darwin wrote near the end of his life:

But then with me the horrid doubt always arises whether the convictions of man’s mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey’s mind, if there are any convictions in such a mind? [Letter to William Graham, 1881]

It is recently the argument presented by Christian philosopher Alvin Plantinga against evolutionary theory – it’s self defeating. If evolution is true, then we have no warrant for thinking that evolution is true, ergo Augustine is right. Or something. I would like to discuss this a little, reprising some arguments Paul Griffiths and I have presented in a forthcoming paper. Below the fold.

First, let’s dispose of one point: Darwin’s Monkey Mind Puzzle was not aimed at debunking our knowledge of the natural world. He did not admit a fatal flaw in his own metaphysics or epistemology. The context of that quote, used by Plantinga and many others is this:


I hope that you will not think it intrusive on my part to thank you heartily for the pleasure which I have derived from reading your admirably written ‘Creed of Science,’ though I have not yet quite finished it, as now that I am old I read very slowly. It is a very long time since any other book has interested me so much. The work must have cost you several years and much hard labour with full leisure for work. You would not probably expect any one fully to agree with you on so many abstruse subjects; and there are some points in your book which I cannot digest. The chief one is that the existence of so-called natural laws implies purpose. I cannot see this. Not to mention that many expect that the several great laws will some day be found to follow inevitably from some one single law, yet taking the laws as we now know them, and look at the moon, where the law of gravitation—and no doubt of the conservation of energy—of the atomic theory, &c. &c., hold good, and I cannot see that there is then necessarily any purpose. Would there be purpose if the lowest organisms alone, destitute of consciousness existed in the moon? But I have had no practice in abstract reasoning, and I may be all astray. Nevertheless you have expressed my inward conviction, though far more vividly and clearly than I could have done, that the Universe is not the result of chance. But then with me the horrid doubt always arises whether the convictions of man’s mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey’s mind, if there are any convictions in such a mind?

Clearly this is about reasoning about God and design, not science. Darwin’s “horrid doubt” is whether we can know anything about God, not the world. He sees no need to imply design based on the regularity of the world. When Plantinga and others quote this passage in isolation, they are being somewhat disingenuous.**

So to the main point: if evolutionary theory is true, then are we blocked from thinking that it is true? Clearly not. If it is true then there is no contradiction with our beliefs being formed on the basis of evolutionary processes also being true. It is not a contradiction that if we evolved to believe that we should flee from tigers that we are veridically seeing tigers. But that is not Plantinga’s argument. He wants to say that we have no warrant for accepting there are tigers, because evolution does not track truth, but fitness.

It is true that, all else being equal*, evolution tracks fitness. Does this mean it doesn’t track truth? Sometime yes, when the fitter belief is untrue. Consider the Dunning-Kruger effect – the inability to appropriately measure our own competence can often lead to greater success. But that doesn’t imply that evolution never tracks truth. When fitness correlates with true beliefs, then it certainly can do this. We have a slogan:

Organisms track truth optimally if they obtain as much relevant truth as they can afford, and tolerate no more error that is needed to obtain it.

Any organism that was fitter with consistently false beliefs would be something of a philosophical miracle, akin to a P-Zombie or a Swampman. When true beliefs are causally relevant to fitness, then we might expect organisms, including those endowed with monkey minds, to be able to track truth. Species that have nervous systems respond to environmental cues that are highly relevant to their fitness: von Uexküll called this the Umwelt. The world of primate common sense is our Umwelt.

Scientific theories bootstrap on this Umwelt; we begin by testing distal claims by ordinary observation, and then extend our theoretical reach by increasingly theoretical, but tested and grounded in our Umwelt, observations, as Ian Hacking argued in Representing and Intervening. Science tracks truth because it is able to rely on some degree of truthlikeness for the observational reports that we can generate in our protoscience. [Incidentally, I think this leads to a structural realism of the kind that Psillos proposes.]

So the claim that if we are mammals we should not believe what we say (on those grounds) fails. Mammals can be right, and we have sufficient warrant to believe those things that depend upon their truth for their success. We can be mistaken, but we trade off false positive against false negatives, or type I and type II errors.

Hitchens would be wrong if he thought that being mammals debunked one set of views but not another if he held that there was something misleading to our beliefs in being a mammal; he would then be subject to a self-defeating argument, a tu quoque; but he need not think that. His opponents think that, but he can happily think that being a mammal is a state consistent with both true and false beliefs. Only those who think humans are somehow more special than just being a species makes them have that problem.

* Assuming that selection is occurring for the property in question. We should really be clear here: natural selection tracks fitness. Evolution is a far broader church than natural selection, a point noted as far back as you care to go, all the way to Darwin’s Origin, in the third edition.

** Late note: Reading through the book listed below I discover that Plantinga knows this, as he buries acknowledgement of it in a footnote. But this doesn’t excuse the mendacity, it only exacerbates it. Anyway, if he had read the letter, which has been published since the turn of the 20th century, it would have been entirely obvious, so I can only assume this is a deliberate piece of misdirection.

For an introduction to the extensive philosophical literature on Plantinga’s argument see James K Beilby, ed., Naturalism Defeated?: Essays on Plantinga’s Evolutionary Argument against Naturalism (Ithaca, NY: Cornell University Press, 2002).


  1. jimhexis jimhexis

    Critics of natural selection are right to point out that adaptation is limited to what is possible. The ancestors of modern insects could develop wings but not ESP because there ain’t no such thing. But this kind of argument has other implications. In developing a capacity for rational thought, human beings did not evolve to have the most favorable cognitive mechanism for survival but at best the most favorable possible mechanism. Logic is probably good for you and your heirs on the average, but that doesn’t mean it can’t sometimes be a bad thing to be stuck with the truth when a useful error would be better. You wins a few and you loses a few.

  2. HP HP

    I’m not a great fan of Christopher Hitchens — I think he’s a stopped clock and the worst of the spokesman for “New Atheism” — but is it true that he reserves the epithet “mammal” only for those he disagrees with? That strikes me as suspect.

    I know I’m a mammal, and I know that when I find myself in the kitchen with no idea why, it’s not because I “forgot” why I got out of my chair, but that there was a buildup of lactic acid in my tissues while I was reading a book or watching a movie.

    • John Wilkins John Wilkins

      I actually have never read Hitchens, or Harris for that matter, apart from what’s been on the web. I wasn’t commenting on their views specifically, but the general argument that derives from Plantinga.

  3. This all reminds me of one of my favourite quotes, of which I have unfortunately forgotten the source:

    If our brains were simply enough that we could understand them, then we would not be intelligent enough to do so.

  4. Plantinga’s argument (and other similar ones I’ve heard) strikes me as being just a dressed-up version of a stoned undergrad exclaiming “Hey, how do we know we aren’t all living in the Matrix?” Well, we don’t — we live, for all practical purposes, in the reality our perception and cognition has constructed for us, and as long as it doesn’t get us killed (too early, too often), that’s good enough. If Real Reality[tm] is otherwise, we have no way of knowing that, and it’s a stupid question.

  5. Animal Annie Animal Annie

    The fact that I am able to think abstractly and question the reason for my existence doesn’t mean that I’m not a mammal. I’m just a mammal with a highly complex brain.

  6. Are we really living in the Matrix? Does it matter, as long as we exist?

    • bob koepp bob koepp

      Does it matter? Only to the extent that truth matters to mammals with highly complex brains.

  7. John, nice skewering of Platinga’s misquote. This whole thing belongs as a cross post on PT as well.

  8. Daffyd ap Morgen Daffyd ap Morgen

    The critiques of evolution and Darwin’s Theory have always been moral, not scientific. Evolution and it’s study are based not on relative underpinnings nor moral conclusions, but on measurements, physical standards and constants. All of the arguments against evolution boil down to “We don’t like it for [insert reason here]; therefore it is not true.”

  9. Johnson’s and Plantinga’s argument is one of the few arguments that I have an active emotional dislike for. This style of argument always struck me presuppositionalist-style nonsense. It confuses certain knowledge with probable knowledge. Moreover, it misses a fundamental issue: human minds aren’t infallible. We know that without evolution. Just look at how people respond with say the sunk cost fallacy or the Monte Hall problem. Or simply how frequently we make arithmetic mistakes or misremember. The notion that evolution somehow makes any of these problems more serious is absurd.

    Moreover, Christians and theists should be very worried about this style of argument for two reasons. First, one can if one wanted to run the argument in the exact opposite direction and point out that a deity that explicitly controls minds (for example God’s hardening of Pharaoh’s heart in Exodus) renders all attempts at reasoning not only potentially faulty but with no way of even beginning to estimate the Bayesian probability of correctness. Second, the implication from the standard form of the argument seems to be that if evolution is wrong and some form of theism is correct then humans are infallible. Is this the same religion that emphasizes humans fallibility? And emphasizes the infinite mind of God against the tiny, finite minds of humans?

    Overall, this argument is a classic example of the worst sort of rationalization: one that seems to support a specific view one wants to support but that one carefully keeps compartmentalized so it doesn’t contaminate any other views.

    • John Wilkins John Wilkins

      I totally agree about the presuppositionalist nonsense; it seems to me a lot of what Plantinga and Craig argue is based on this Douyeweerdian silliness (no accident D was a legal scholar, IMO). We know that arguments reply on premises – that doesn’t mean everything is a religion.

      I like the point about Pharoah, and shall use it at my earliest convenience. But the more general point is that the Christians seem not to want any kind of a fallibilism in their epistemologies (which is, I think, a kind of psychologism), effectively rendering all knowledge valueless unless supported by their Authority. Plantinga is not so dumb as to assert that, but one wonders what he would think was warrant enough to conclude no God existed…

  10. Soren Soren

    Good to see someone as capable as you tackle Plantinga. I’ve had a couple of bouts with apologetics who just loved Plantingas argument.

    My main vector of attack on it, besides the ones taken from Sobels critiscism, has been to counter his Tiger example.

    I learned long ago that researchers have found that the cats ability to track motion is learned. It must be based on capabilities of its brain, but if you bring up a cat in an environment where the young cat never sees any motion, it will unable to track when adult.

    This makes the ability to track motion a cognitive faculty not a simple sense. This should be obvious since your senses can only see what is, not into the future.

    According to Plantinga there is no reason for cognitive faculties to be predisposed towards truth. But that is simply not so in the case of tracking movement. If

  11. Soren Soren

    Good to see someone as capable as you tackle Plantinga. I’ve had a couple of bouts with apologetics who just loved Plantingas argument.

    My main vector of attack on it, besides the ones taken from Sobels critiscism, has been to counter his Tiger example.

    I learned long ago that researchers have found that the cats ability to track motion is learned. It must be based on capabilities of its brain, but if you bring up a cat in an environment where the young cat never sees any motion, it will unable to track when adult.

    This makes the ability to track motion a cognitive faculty not a simple sense. This should be obvious since your senses can only see what is, not into the future.

    According to Plantinga there is no reason for cognitive faculties to be predisposed towards truth. But that is simply not so in the case of tracking movement. If you want to catch your prey, a false belief as to where it will be in half a second is just not good enough.

    The argument can be extended to many such basic faculties. Beliefs very close to our senses must bear a heavy price if they are very wrong.

    But this has a natural extension. Because we can assume that our beliefs about the persistence of objects, tracking of movement etc have a high probablity of being close to the truth. This means we can test a lot of beliefs not readily confirmed by mere observation.

    For instance the idea that heavy objects fall with a greater acceleration than light objects can be testes, and indeed rejected based on direct observation.

    This generates not doubt about our faculties, but a kind of ladder of beliefs. Beliefs that can be readily tested empirically carry a higher probability of being true, if they pass tests.

    Beliefs not readily tested, such as the existence of invisible entities, such as gods, are harder to defend within a purely evolutionary justification for the ability of our faculties.

    This in fact mirrors the scientific method for acquiring knowledge.

  12. Soren Soren

    Sorry about the double post, my trackpad is playing tricks on me.

  13. TomS TomS

    The Intelligent Design advocates tell us being the product of design is no guarantee of perfection: tail-fins on cars and the urogenital system.

    So what advantage does design give us over evolution for our knowledge-acquisition system?

  14. Allen Hazen Allen Hazen

    The “Plantinga” argument (naturalism casts doubt on human reasoning ability, hence arguments for naturalism are suspect(*)) predates Plantinga (no surprise there…): C.S. Lewis somewhere (don’t remember where: possibly one of the apologetic works like “Mere Christianinty,” but also possibly in an autobiographical one, like “Surprised by Joy”) gives a two or three sentence statement of it, endorsing it as an additional reason for thinking Christian theism a more rational belief than scientific naturalism. When I first heard that Plantinga endorsed the argument (possibly from his own mouth: I attended a Plantinga talk in about 1990), I was astonished: “He’s just giving that old argument I remember from reading C.S. Lewis when I was an adolescent!) I thought to myself.

    Mind you, I think C.S. Lewis deserves a BIT of philosophical respect: his academic career was in English, but he had certainly studied philosophy, and considered applying for philosophy jobs. I think he should be considered a SERIOUS amateur philosopher… and that in his writings can be found (expressed clearly and unpedantically and briefly) ideas that are of some philosophical interest: bits of his writings, i.m.h.o., could be useful in teaching philosophy to undergraduates.

    As for the argument… My feeling is that it is an argument for a kind of general scepticism. Science tells us that human reason evolved to provide rough-and-ready, rule-of-thumb, guidance in immediate practical matters, not to “track truth” globally. Hence ALL our conclusions should be held tentatively. What it DOESN’T do is tell selectively on one side or another of particular questions. Perhaps the evolutionary naturalist is tempted to say “Naturalism is overwhelmingly, utterly, totally, more plausible than the alternative.” Taking the “Plantinga” argument on board, they can still say “Naturalism is more plausible than the alternative, by as wide a margin as any theoretical position EVER is,” and just admit that that margin of certainty is — like averything else in human life — less than absolute!

  15. Allen Hazen Allen Hazen

    (*) That parenthetical statement is just for reference purposes: it isn’t intended as an adequate statement of the argument.
    … And, for that matter, my evaluation of the argument in my last paragraph of the preceding post… I think the argument raises serious epistemological issues that would take at least a full-scale paper to address, and I haven’t done that.

  16. James F James F

    Just stopping in to give you kudos for comparing The Bloodhound Gang to Andrew Marvell. Someone needs to forward this to Messers. Jimmy Pop, DJ Q-Ball, Jared Hasselhoff, The Yin, and Daniel P. Carter.

  17. Argon Argon

    Well, the fact is that humans do not have a perfect view of world. We routinely make mistakes and routinely confront illusions, misperceptions and intellectual journeys up the wrong path. This is as Plantinga would suggest.

    What Plantinga grossly underestimates is the effect of repeated trial and error — It optimizes for survival on one scale and for ‘better mapping’ of reality on another. Our initial notions about the world are quite bad, however thanks to our memory capabilities, we readjust our maps over time.

  18. Pierce R. Butler Pierce R. Butler

    Being mammalian may indeed contribute to our intellectual deficits, but some field work will show that reptilian, avian, piscine and other lifeforms are also prone to error.

    However, has anyone ever seen a fungus make a mistake?

  19. H.H. H.H.

    The reason Plantinga’s argument is vacuous is because he offers no real solution to the problem he poses. Sure, evolved brains are subject to error. We know this. It can be demonstrated in a variety of instances. But that doesn’t mean naturalism is self-defeating. How does supernaturalism solve the problem? It doesn’t. Innate cognitive biases would still exist even if we assume god built our brains using magic, only now we have additional problem of being forced to conclude that whichever god created our brains made them purposefully inaccurate. Plantinga might have faith that the Christian god is basically a trustworthy guy and wouldn’t give us brains that were completely unreliable, but he can’t demonstrate such a thing, which he must to do if he would have us reject materialism on the mere possibility that it doesn’t lead to brains with 100% accuracy. Hell, he can’t even demonstrate that the Christian god exists, or that he’s responsible for creating us. Maybe we’re all brains in vats being duped by demons for their own sadistic pleasure.

    Bottom line, assuming the supernatural does nothing to solve the problem of doubting our own convictions. If Plantinga thinks he can trust his brain solely because he believes it was made by a magic man in the sky, then he’s simply delusional, and the certainty of his convictions is utterly baseless.

    • John Wilkins John Wilkins

      I think Plantinga is a little more sophisticated than you give credit – he’s not trying to show that God gives us warrant, but only that if you are naturalistic you have no warrant for your beliefs. Of course it is a question begging exercise and also involves an implicit false dichotomy, but he would, I expect, say that belief in God is warrantless but provides all the rest of the warrant you need.

      • H.H. H.H.

        John, you’re right that I don’t give Plantinga much credit, because imo his “sophistication” is actually sophistry. I agree that he doesn’t show how God gives us warrant, but I think that’s essentially dishonest. I understand that one may argue against one position without necessarily arguing for another, but in this case, there are really only two options: materialism or supernaturalism. If Plantinga’s is saying that he’s managed to invalidate materialism, then he’s also implicitly declaring that supernaturalism must be correct by default. Except when we examine the question of whether assumptions of supernaturalism give us warrant to trust our perceptions, we find that it does not. The same problems of uncertainty still exist. One cann0t sweep those problems under the rug simply by claiming faith in a benevolent god. That’s merely assuming your conclusion. (My beliefs are trustworthy because I believe I am not deceived.)

        • John Wilkins John Wilkins

          Don’t misundertake me, as Cheech or Chong once said; I am not giving Plantinga’s argument kudos. I am merely saying that we should engage with the best interpretation of it before we dismiss it. I agree with your analysis.

  20. Bryson Brown Bryson Brown

    One point I’ve always made when answering this silly argument of Plantinga’s is that it’s wrong from the ground up, since it focuses on the priors (assume organism X has evolved and has beliefs; how probable are its beliefs to be true). But what we should assign as probabilities now are posteriors: given all the evidence we have (of, for example, our ability to come to independent agreement, including agreement on the ways in which our evolutionary heritage makes some of our perceptions anthropocentric and how to correct for that), what is the probability that our methods are reliable?

    It’s like winning a lottery: the prior probability of winning is very low, but that’s not a defeater for the person holding the winning ticket when she checks her numbers.

    Another thread in the argument is the strong assumption that beliefs can be attributed in general entirely independently of whether they are true. But if that’s really right, I don’t see any way out of the problem of the criterion- for theists or anyone else.

    A friend heard Plantinga present this line some years ago in Amsterdam– after, he overheard two Dutch reform preachers talking about the argument– one said something like, “if that’s the kind of argument we need to use, we’re really in trouble.” I agree.

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